Photosensitizing dye of the isocyanin type



UNITED STATES PATENT OFFICE.

ELLIOT Q. ADAMS, OF BERKELEY, CALIFORNIA, AND HERBERT L. HALLER, 0F CINCINNATI, OHIO.

No Drawing.

Specification of Letters Patent.

Patented Apr. 12, 1921'.

Application filed May 28, 1920. Serial No. 385,061.

(FILED UNDER THE ACT OF MARCH 3, 1883, 22 STATIL, 625.)

To all whom it may concern:

Be it known that we, ELLIOT Q. ADAMs and HERBERT L. HALLER, citizens of the United States of America, and employees of the Department of Agriculture, residing in the city of Berkeley, county of Alameda, State of California and in the city of Cincinnati, county of flamilton, State of Ohio, respectively (whose post-ofiice address is Department of Agriculture, Washington, D. C.,) have invented new and useful Photosensitizing Dyes of the Isocyanin Type, of which the following is a specification.

Dyes of this type are known to be substituted ammonium salts, the sensitizing action bein due to the positive ammonium radical. H ence, the nature of the negative radical will be of influence only in so far as it affects adversely the solubility of the compound or possesses deleterious action of its own. It; will therefore be possible to use any quaternary compounds satisfactory in these respects.

This application is made under the act of March 3, 1883, chapter 143 (22 Stat. L., 625), and the invention herein described and claimed may be used by the Government of the United States or any of its officers or employees in the prosecution of work for the Government, and any person in the United States, either on public or private work, without payment to us of any royalty thereon.

It is known that a mixture of the quater-.

nary halids (or other addition products) of quinolin and quinaldin,-or, more generally, of an a-methylated and a y-unsubstituted pyridin base,yields with strong bases in alcohol solution a dye of the iso-cyanin type; while a mixture of the quaternary halids (or other addition products) of quinolin and le idin,--or, more generally, of a y-methylate and a -unsubstituted pyridin base,yields with strong bases in alcohol solution a dye of the cyanin type. By a-methylated pyridin bases are meant derivative-s of pyridin, quinolin, or related bases, having a methyl group adjacent to the nitrogen of the heterocyclic ring, and by y-unsubstituted pyridm bases and y-methylated pyridin bases are meant derivatives of pyridin, quinolin, and related bases, having, respectively, a hydrogen and a methyl group diametrically opposite the nitrogen of the heterocyclic ring. By strong bases are meant sodium and potassium hydroxid, silver oxid, and the methylates and ethylates of sodium and potasslum.

V Ve have found that the quaternary hallds or other addition products of sufiiciently pure lepidin, or other 'r-methylated a-unsubstituted pyridin bases, yield when treated, under suitable conditions, with strong bases in alcohol solution, dyes of the iso-cyanin type. It is to be noted that these dyes, while similar, are not. chemically identical with those produced from derivatives of quinaldin. High temperature, high concentration of reagents and low radical weight of the alkyl group attached to the nitrogen of the heterocyclic ring favor this type of condensation.

While the use of alcohols as the solvent is not indispensable, since the solvent does not take part in the reaction, we have ob tained better results in methyl and ethyl alcohol than in any other solvents.

The following examples will serve to illustrate the preferred procedure. The invention, however, is not confined to these examples. The parts are by weight.

Example 1:2.85parts of lepidin methiodid are dissolved in 20 parts of absolute methyl alcohol and heated to boiling. A solut10n of sodium methylate, prepared by dissolving 0.115 part of metalllc sodium in 8 parts of absolute methyl alcohol, is added, The boiling is continued a few minutes, after which the mixture is allowed to cool very slowly. After 24 hours the separated dye.

is filtered oil, washed with small amounts of ice-cold meth 1 alcohol followed by ethyl ether, and alr-dried. The ield is approximately 0.8 part of a purp e-drab felt of fine needles. A further yield may be obtained by cautious concentration of the mother li 110rs..

Examp e 2: 1.5 parts of lepidin ethiodid are dissolved in 16 parts of absolute methyl alcohol and heated to boiling. A solution of sodium methylate, prepared by dissolving 0.058 part of metallic sodium in 4 arts of absolute methyl alcohol, is added. he boiling is continued until the volume is reduced to one-fifth, after which the mixture is allowed to cool very slowly. After 24 hours the separated dye is filtered off, washed with small amounts of ice-cold methyl alcohol, mixtures of methyl alcohol and ethyl ether, and finally ether alone. The yield is approximately 0.2 part of a green crystal powder with pronounced metallic luster. A further yield may be obtained by cautious concentration of the mother liquor.

Example 3: 4.5 parts of p-tolulepidin methiodid are dissolved in 32 parts of warm absolute methyl alcohol, and very gradually added to a solution of 2.5 parts silver nitrate in 64'parts hot absolute methyl alcohol. The precipitate is filtered off with suction. The filtrate is concentrated to half its volume and a solution of sodium methylate made by dissolving 0.172 part of metallic sodium in 12 parts absolute methyl alcohol is added gradually. The solution is concentrated to half its volume and allowed to cool very slowly. After 24 hours the separated dye is filtered off, washed with small amounts of ice-cold methyl alcohol,- followed by ethyl ether, and air-dried. The yield is approximately 0.4 part of a steel blue powder consisting of aggregates of microscopic crystals.

The products in all the above examples dissolve in alcohol, chloroform, acetone, etc-., with the pink color characteristic of the iso-cyanins.

Having now fully described our invention, what we claim and desire to protect by Letters Patent is- 1. Dyes of the iso-cyanin type produced by the action of strong bases in alcohol so-' lution upon the alkyl halids of lepidin.

2. Dyes of the iso-cyanin type produced by the action of strong bases in alcohol solution upon the quaternary addition products of ymethylated ran-unsubstituted pyridin bases.

3. Dyes of the iso cyanin type produced by the action of strong bases upon the quaternary addition products of -methylated oz-unsubstituted pyridin bases.

4. The process of producing photographic sensitizing dyes of the iso-cyanin type by the action of sodium methylate in absolute methyl alcoholic solution upon the quaternary halids of lepidin.

5. The process of producing photographic sensitizing dyes of the iso-cyanin type by the action of sodium methylate in absolute methyl alcoholic solution upon the quaternary addition products of y-methylated oz-unsubstituted pyridin bases.

6. The process of producing photographic sensitizing dyes of the iso-cyanin type by the action of strong bases in alcoholic solution upon the quaternary addition products of y methylated a-unsubstituted pyridin bases.

7. The process of producing dyes of the iso-cyanin type by the action of strong bases upon the quaternary addition products of -methylated a-unsubstituted pyridin bases.

In testimony whereof We aflix our signatures in the presence of two subscribing witnesses.

ELLIOT Q. ADAMS. HERBERT L. HALLER.

Witnesses:

L. A. MIKEsKA, H. WALES. 

